The present invention relates to a refractory plate assembly for use in a sliding closure unit employable in controlling the discharge of molten metal from a metallurgical vessel. The present invention particularly relates to such an assembly of the type including a refractory plate having a planar sliding surface and mounted within a jacket or shell, for example formed of sheet metal, with an insulation material therebetween. The present invention even more particularly relates to such an assembly also including a refractory outlet sleeve or tube joined to the refractory plate member and extending therefrom through a base portion of the shell.
In this type of refractory plate assembly, i.e. so-called two-component plates, known for example from DE-AS 24 09 699, the object generally is to achieve a maximum service life of the assembly and at the same time to employ the smallest possible amounts of high-grade and expensive wear-resistant refractory materials that form the sliding surface. That is, the sliding surface generally must be formed of an expensive high-grade refractory material, such as an oxide ceramic. For reasons of economy however it is desired to form the portions of the assembly that do not contact the molten metal with a less expensive low-grade refractory material, such as refractory concrete which has a low density and thus acts as a thermal insulator with respect to the refractory plate member defining the sliding surface. However, the use of such different refractory materials in this prior art manner has a number of inherent disadvantages, primarily involved in production. Particularly, molding of the plate member defining the sliding surface directly into refractory concrete involves a difficult drying or curing process in order to attempt to prevent the occurrence of stress in the refractory concrete backing material.